The present invention relates to the general technical field of hot beverage making machines in which a hot beverage is produced by a process that can be termed lixiviation, i.e. passage of hot water, as a solvent, through a ground product having a defined granulometry.
The invention more specifically concerns a hot beverage machine, and in particular a coffee maker, having at least one hot water outlet disposed above a filter holder, a hot water distribution plate for distributing water across the surface of the ground product contained in the filter holder, the plate being provided with perforations and being located under the water outlet, as well as means for regulating the distribution of water.
It has already been attempted to master the spraying of coffee grounds in order to obtain an optimum extraction of the essence and flavors contained in the grounds. To this end, French application FR-A-2625893 discloses equipping a spraying head with a valve which is controlled by a delay device. The valve can occupy a first position corresponding to the start of the operating cycle of the coffee maker and inducing, by the intermediary of perforations, a peripheral spraying of the coffee grounds. In a second stage of the operating cycle of the coffee machine, the valve occupies a second position controlled by the delay device, the second position being one in which the coffee grounds are sprayed in their central zone. Such a device arrives, in the end, at a spraying of the coffee grounds which is variable in time, shifting in a discontinuous manner from a peripheral spraying to a central spraying of the coffee grounds.
Such a device can be considered as making a positive contribution to the general goal of mastering the phenomenon of lixiviation and more generally of mastering the extraction of the essence of ground coffee, but it is in order to consider that this prior art device also has shortcomings. Thus, its fabrication requires the assembly of supplemental pieces such as a valve and a delay device. Moreover, this device does not allow account to be taken of variations in granulometry or type of grounds, which, overall, does not permit the user to himself regulate the flavor of the beverage which he desires to obtain.
It has also been disclosed, in German application A-2751310, to improve the extraction of essence from ground coffee by permitting the user to himself regulate the zone of impact of the water on the coffee grounds. This prior art device includes a distribution plate provided with peripheral orifices and a central orifice having a larger diameter. Water flows onto the grounds across the distribution plate, starting from a hot water outlet disposed above the plate and along the axis of the central orifice. Mastery of the distribution of water is assured by a regulating means constructed in the form of a deflection plate provided with a position regulating lever. The deflection plate can thus occupy a position beneath the hot water outlet opening, or a second position spaced from the axis of hot water flow. The user can thus regulate the distribution of hot water on the surface of the grounds by adjusting the position of the deflection plate which in its position beneath the outlet opening leads hot water to spray the periphery of the grounds, and in the other position leads the hot water into contact with the central zone of the grounds.
It must therefore be considered that this device permits the user to himself regulate to a certain extent the quality of the extraction of essence from the grounds, in order to take into account for example the quantity or the type of grounds utilized. It must however be recognized that this device only permits a limited regulation of the flavor of the beverage obtained because there are, in the final analysis, only two different extraction positions.